Efficacy and
safety of apixaban compared with warfarin according to
patient risk of stroke and of bleeding in atrial fibrillation: a secondary analysis of a randomised controlled trial.
Lopes RD, Al-Khatib SM, Wallentin L, Yang H, Ansell J, Bahit MC, De Caterina R, Dorian P, Easton JD, Erol C, et al. Lancet. 2012 Nov 17; 380(9855):1749-58. Epub 2012 Oct 2.